Project Abstract The principal objective of the National HIV Behavioral Surveillance System (NHBS) is to monitor risk behaviors and access to prevention services among three populations at highest risk for HIV infection in the United States: men who have sex with men (MSM), injection-drug users (IDU), and heterosexuals at increased risk for HIV (HET). The NHBS strategy involves rotating 12-month cycles of surveillance activities in these three populations. The Denver Metropolitan Statistical Area (MSA) has been involved with NHBS since its inception in 2003. The Colorado Department of Public Health and Environment (CDPHE), as the state health department, will serve as the grantee for this award with the primary responsibility for meeting stated objectives contracted to Denver Public Health (DPH), the local city health department. In order to achieve the objectives outlined in the funding announcement, we propose the following specific aims: 1) To assess and monitor risk behaviors and access to prevention services among three populations at highest risk for HIV infection in the Denver MSA: MSM, IDU, and HET, 2) To evaluate the seroprevalence of HIV, HCV, and HBV infection in the MSM, IDU, and HET populations at risk for HIV infection in the Denver MSA, 3) To conduct new HIV testing technologies during the MSM cycle, and 4) To analyze, disseminate, and utilize NHBS data to realize the greatest public health impact in the Denver MSA.